An SiC crystal has a large band gap and also has maximum breakdown electric field and thermal conductivity higher than those of silicon (Si), and the SiC crystal has carrier mobility as high as that of Si and it is high also in electron saturation drift velocity and breakdown voltage. Therefore, application to a semiconductor device required to achieve higher efficiency, higher breakdown voltage and larger capacity is expected.
An SiC crystal employed in such a semiconductor device is manufactured with a sublimation method representing a vapor phase epitaxy method, as disclosed, for example, in Japanese Patent Laying-Open No. 2005-008473 (PTL 1), Japanese Patent Laying-Open No. 2005-314217 (PTL 2), and the like.
PTL 1 discloses lowering in nitrogen concentration in a grown SiC crystal by using a graphite crucible of which impurity nitrogen concentration is not higher than 50 ppm for growing an SiC crystal. PTL 2 discloses a method of growing an SiC crystal by using a carbon source material having boron concentration not higher than 0.11 ppm and a silicon source material having boron concentration not higher than 0.001 ppm.